Vehicle airbags are safety devices that deploy toward the interior of a vehicle to help protect its occupants from injury in the event of a crash. Airbags may be concealed behind or beneath an interior panel during normal vehicle operation until such an event. When the airbag deploys, it typically does so through a deployment opening formed in or around the interior panel. The deployment opening may be pre-formed in the panel, the panel may move away to reveal the opening, or the opening may be formed during airbag deployment at a pre-determined location in the panel. Where formed during deployment, a tear seam may be provided in one or more components of the panel to control the location of material separation during airbag deployment.
U.S. Pat. No. 6,089,642 to Davis et al. discloses typical tear seam shapes. In each embodiment described in the Davis patent, rectangular airbag doors are concealed beneath a layer of material having a tear seam formed along its underside. The tear seams are formed along the three unhinged sides of the underlying airbag doors. In one example, there is a single rectangular airbag door hinged on one side and a U-shaped tear seam formed in the overlying layer of material. The U-shape follows the shape of the three unhinged sides of the airbag door. In another example, there are two rectangular airbag doors, each hinged on one side, and the tear seam is in an H-shape. The H-shape follows the shape of the dual airbag doors, with the vertical bars of the H-shape following side edges of the airbag doors and the cross-bar of the H-shape following the other unhinged sides of the airbag doors.